Pultrusion Method and Related Article

ABSTRACT

A method of forming a reinforced composite structure comprises providing a plurality of fiberglass rovings to a resin applicator. The plastic applicator has an inlet, an outlet, and a plastic applicator cavity such that the rovings enter the plastic applicator through the inlet and exit through the outlet. The inlet and outlet are relatively positioned to spread out the rovings. Resin-containing rovings are directed between a first fiberglass matt and a second fiberglass matt and then cured. A joint that connects two frame members formed by the method of the invention is provided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to methods of forming frame members havinghigh reinforcement concentrations and complex cross-sections bypultrusion and to articles formed therein.

2. Background Art

Pultrusion is a process in which reinforced solid or hollow plasticstructures of uniform cross-section are formed in a continuous manner.In the pultrusion process, a fiber reinforced material is pulled throughan open resin impregnation bath and then a shaping die in which theresin is subsequently cured. In the final step, the pultruded structureis sawed off at a desired length. Typically, pulling is accomplished bya continuous belt or reciprocating clamping system at speeds from about0.5 to about 2 m/minute. The resin must cure quickly because of the highspeed and continuous nature of the process.

In general, pultruded structures are elongated structures of uniformcross-section. Reinforcements are usually added and aligned along theelongated direction. Other reinforcement types include continuousfilament mats and fabrics, which provide transverse reinforcement, andveils for surface finish. Several suitable guiding systems positionedbetween creels and the curing die, allow the shaping and placement ofeach reinforcement type at the right location Due to the continuousnature of the pultrusion process, composites of any desired length canbe produced. Pultruded parts are used in electrical, corrosionresistant, building and consumer goods applications. Commercialapplications for pultruded structures include structural shapes likeI-beams, channel sections, tool handles, and window framing.

As set forth above, pultruded objects typically include reinforcementswhich enhance the mechanical strength of such structures. Commonly usedreinforcements include glass, carbon and aramid fibers. When present,the glass reinforcements range from 30 to 70% by weight. Glassreinforcements which provide longitudinal reinforcement are usuallyadded as single-end rovings arranged in one or more creels. Fillers mayalso be combined in the pultrusion process to provide additionalproperties to pultruded parts. Such fillers include, for example,fillers that provide fire retardancy, color, cost reduction, and thelike.

Although the pultrusion process is one of the most cost-effectivemethods for the production of composite materials, there are still anumber of areas open for improvement. For example, the open nature ofthe resin impregnation bath presents environmental issues as well asproduction efficiency issues. The prior art pultrusion methods ingeneral are not able to form frame members for building enclosureapplications that have the requisite combination ofproperties—mechanical strength, aesthetically pleasing surface finish,and cost effective production. Accordingly, building enclosurestypically are formed from vinyl covered aluminum frame members with thealuminum providing strength and the vinyl providing an aestheticallypleasing appearance.

Accordingly, there exists a need in the prior art for pultrusion methodsthat produce frame members with suitable strength and appearance forbuilding enclosure applications.

SUMMARY OF THE INVENTION

The present invention solves one or more problems of the prior art, byproviding in one embodiment a method of forming a reinforcedfiberglass-plastic composite structure. The method of the inventioncomprises providing a plurality of fiberglass rovings to a resinapplicator. The plastic applicator has an inlet, an outlet, and aplastic applicator cavity such that the rovings enter the plasticapplicator through the inlet and exit through the outlet.Characteristically, the inlet and outlet are relatively positioned tospread out the rovings. Moreover, the rovings are embedded with a liquidresin within the plastic applicator cavity to form resin-containingrovings. At least a portion of the resin-containing rovings are directedbetween a first fiberglass matt and a second fiberglass matt. Next, theresin-containing rovings, the first fiberglass matt, and the secondresin-containing matt are directed into a curing chamber. Subsequently,the resin-containing rovings positioned between the first and secondfiberglass matts are cured to form the fiberglass-plastic compositestructure. The reinformed plastic composite structure emerges from thecuring chamber at a predetermined linear speed.

In another embodiment of the invention, a joint that connects two framemembers together is provided. The joint of this embodiment includes afirst frame member attached to a second frame member via a fastener. Thefastener of this embodiment has a body section, one or more flangesections extending from the body section, an insert section extendingfrom the body section, and an angled stop surface defined by a surfaceof the body section. Characteristically, the angled stop surface isoriented at a mating angle that matches the angle of an end second framemember such that when the insert section is positioned within theinterior cavity the first end is adjacent to the angled stop surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a frame member made by an embodiment ofthe method of the invention;

FIG. 1B is a cross-sectional view of a frame member made by anembodiment of the method of the invention;

FIG. 2 is an idealized schematic of a pultrusion system of theinvention;

FIG. 3 is a perspective view of an apparatus implementing the methods ofthe invention;

FIG. 4 is a cross-section illustrating a compound structure withresin-containing rovings positioned between first fiberglass matt andsecond fiberglass matt;

FIG. 5A is a front view of a variation of the resin applicator of theinvention;

FIG. 5B is a cross-sectional view of a variation of the resin applicatorof the invention;

FIG. 6 is a perspective view of a mechanism for aligning the curingsection to the preform section;

FIG. 7 is a perspective view of a variation of the joint of the presentinvention;

FIG. 8A is a perspective view of a fastener that connects the end of asecond frame member to a central location on a side of a first framemember;

FIG. 8B is a perspective view of a fastener that connects the end of asecond frame member to an end position on the side of a first framemember;

FIG. 9 is a top view of the fastener of FIG. 8A;

FIG. 10 is an exploded perspective view of a cathedral wall fabricatedusing one or more components of the present invention; and

FIG. 11 provides a simple perspective view of a cathedral wall.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Reference will now be made in detail to presently preferred compositionsor embodiments and methods of the invention, which constitute the bestmodes of practicing the invention presently known to the inventor.

As used herein, “frame members” refers to any beam, girder, or channelstructures that can be attached together in a network to form a windowor a building enclosure.

In one embodiment of the present invention, a method of forming a fiberreinforced article is provided. The method of the present invention iscapable of forming any such article so long as the article has a uniformcross-section. In particular, the method of the present invention isparticularly useful in forming frame members and beams that are used toconstruct building enclosures. Such building enclosures include, forexample, patios, sunrooms, green houses, and the like. With reference toFIGS. 1A and 1B, illustrations of a representative frame member producedby the method of the present invention are provided. Frame member 10 isextended along direction d₁ having a uniform cross-section as shown inFIG. 1B. Wall 12 of enclosure 10 defines hollow cavity 14 which extendsalong direction d₁. Hollow cavity 14 includes rectangular cavity section20, 22 and central cavity section 24. Rectangular cavity section 20, 22and central cavity section 24 together are arranged in a shaperesembling the letters I or H with indentations 26, 28. Wall sections30, 32 overhang rectangular sections 20, 22 in a flange-like manner.Wall section 30 is characterized by width w₁ and wall section 32 ischaracterized by width w₂ where w₁ is greater than w₂.

With reference to FIGS. 2 and 3, schematics of a pultrusion systemimplementing the method of the invention are provided. FIG. 2 is anidealized schematic of a pultrusion system of the invention. FIG. 3 is aperspective view of an apparatus implementing the methods of theinvention. Pultrusion system 50 includes preform section 52 and curingsection 54. Preform section 52 includes resin applicators 56 whichapplies a resin to a plurality of fiberglass rovings 58 (only a fewrepresentative rovings are illustrated). Fiberglass rovings 58 aretypically provided from a plurality of creels (not shown). Firstfiberglass matt 60 is provided from roll 62 to forming collar 64. Firstfiberglass matt 60 is subsequently folded to form a hollow cavity viaforming collar 64. Mandrel 66 is located within this cavity. Fiberglassrovings 58 are positioned about and proximate to first fiberglass matt60. The positioning of fiberglass rovings 58 about fiberglass matt 60 ismediated by carding plates 70, 72 which include a plurality of holesthrough which fiberglass rovings 58 travel. Resin applicators 56 eachhave an inlet, an outlet, and a resin applicator cavity. Fiberglassrovings 58 enter resin applicators 56 through the inlet, and exitthrough the outlet such that the inlet and outlet are relativelypositioned to spread out fiberglass rovings 58. Fiberglass rovings 58are embedded with a liquid resin within the plastic applicator cavity toform resin-containing rovings. Also within preform section 52, secondfiberglass matt 80 is provided from matt roll 82. Second fiberglass matt80 moves along forming collar 84 and is subsequently folded onto itselfto form a cavity in which fiberglass rovings 58 and first fiberglassmatt 60 are positioned (i.e., second fiberglass matt 80 surroundsfiberglass rovings 58 and first fiberglass matt 60).

With reference to FIG. 4, a cross-section illustrating a compoundstructure with resin-containing rovings 58 positioned between firstfiberglass matt 60 and second fiberglass matt 80 is provided. Thiscompound structure is directed into forming chamber 86 which acts toform a preform shape corresponding to the cross-section of the finalproduct. Additional liquid resin is optionally provided to formingchamber 86 via inlet 88. It should be appreciated that the preform shapewill not, in general, have exactly the same dimensions of the finalcross-section. Instead, only sufficient shaping for final curing insubsequent stages is performed within forming chamber 86 on firstfiberglass matt 60 and second fiberglass matt 80 with theresin-containing rovings positioned in-between. Subsequently, theresin-containing rovings, the first fiberglass matt 60, and secondresin-containing matt 80 are directed into curing section 54. Typically,curing section 54 comprises curing dies 90, 92. While the pultruded partmoves through curing dies 90, 92 curing is accomplished with the finalcompression and shaping being applied to the pultruded structure. Afteremerging from curing section 54, the emerging compound structure 94 iscut at a desired length to form the reinforced article (e.g., the framemember).

Still referring to FIGS. 2 and 3, it should be appreciated that themethods of the invention, like all pultrusion methods are continuous innature. During operation, the emerging compound structure 94 is pulledfrom curing section 54 which in turn causes first fiber matt 60, andsecond fiber matt 80 to be provided in a continuous fashion to preformsection 52 and curing section 54. Pulling is typically achieved by acontinuous belt system or a reciprocating clamping system. Emergingcompound structure 94 emerges from curing section 54 at a predeterminedlinear speed. Typically, this predetermined linear speed is betweenabout 1 ft/min to about 20 ft/min.

With reference to FIGS. 5A and 5B, illustrations of a variation of resinapplicator 56 are provided. FIG. 5A is a front view, and FIG. 5B is across-sectional view of resin applicator 56. Resin applicator 56contains the liquid resin which is applied to fiberglass rovings 58 asset forth above. Fiberglass rovings 58 enter resin applicator 56 viainlets 100. Typically, inlets 100 are slot-shaped. Resin located withincavity 102 is picked up by fiberglass rovings 58. Typically, thefiberglass rovings are saturated with the liquid resin. After picking upthe resin, the rovings exit via exits 104 which are also typicallyslot-shaped. Contact by fiberglass rovings 58 with one or more of thesurfaces that define inlets 100 and outlets 104 act to advantageouslyspread out fiberglass rovings 58. Such contact is enhanced by havinginlets 100 vertically offset from outlets 104. It should be appreciatedthat although resin applicator 56 of the present invention is not airtight, the closed nature of this applicator offers substantialimprovement over the open resin baths of the prior art.

With reference to FIG. 6, a perspective view of a mechanism for aligningcuring section 54 to preform section 52 is provided. Curing section 54which includes dies 90, 92 is aligned along directions d₃ and d₄ viapositioning devices 110, 112. Positioning device 110 moves curingsection 54 about pivot point 114 along direction d₃ which is ahorizontal direction normal to the direction at which material movesthrough pultrusion system 50. Positioning device 112 moves curingsection 54 in vertical direction d₄ about pivot point 114.

As set forth above, liquid resin is applied at various stages of themethods of the invention. Such application occurs in resin applicators56 and in forming chamber 86. Virtually any resin which is capable ofcuring in the time compatible with the linear speed of the process maybe used. Typically, such resins are thermoset resins. A particularlyuseful example of a thermoset resin is an unsaturated polyester resin.Specific unsaturated polyester resins include resins based onmaleic-anhydride, isophthalic acid, terephthalic acid, orthophthalicacid, dicyclopentadiene, and vinyl ester chemistries.

With reference to FIG. 7, illustration of an embodiment of a joint inwhich two frame members are connected together is provided. FIG. 7 is aperspective view of a variation of the joint of the present invention.Joint 120 attaches two frame members together. First frame member 122includes a first substantially rectangular surface 124 which has firstwidth w₁. Second substantially rectangular surface 126 has second widthw₂. First width w₁ is greater than second width w₂. First frame member122 includes wall 132 that defines interior cavity 134 and indentations136, 138. Similarly, second frame member 140 includes wall 142 thatdefines interior cavity 144 and indentations 146. Moreover, second framemember 140 includes first end 152, second end 154, third substantiallyrectangular surface 156, and fourth substantially rectangular surface158. First end 152 is angled relative to a plane perpendicular to thethird substantially rectangular surface 156. First frame member 122 isconnected to second frame member 140 via fastener 160. In a variation ofthis embodiment, second frame member 140 is of a similar design to firstframe section 122 with third substantially rectangular surface 156having a width that is greater than the width of a fourth substantiallyrectangular surface 158. Typically, interior cavity 134 and interiorcavity 144 may be of rectangular cross-section or of a non-rectangularcross-section. Advantageously, the methods of the invention set forthabove allow for complex cross-sections with protrusions and indentationsbeing incorporated in the frame members. In a useful variation, one orboth of frame members 122, 140 have a non-rectangular cross-section thatis substantially I-shaped or H-shaped as set forth above. In stillanother variation, frame members 122, 140 have substantially the samecross-section.

With reference to FIGS. 7, 8A, 8B, and 9, various views of fastenervariations are provided. FIG. 8A is a perspective view of a fastenerthat connects the end of second frame member 140 to a central locationon a side of first frame member 122. FIG. 8B is a perspective view of afastener that connects the end of second frame member 140 to an endposition on the side of first frame member 122. FIG. 9 is a top view ofthe fastener of FIG. 8A. Fastener 160 includes body section 162 and oneor more flange sections 164, 166. Flange sections 164, 166 extend frombody section 162. Flange sections 164, 166 attach to side 168 of firstframe member 122. Attachment may be accomplished with bolts that arepassed through holes 170. In the variation shown in FIG. 8A, fastener160 includes flanges on both of sides 172, 174. Moreover, on each sidetwo flanges sections are utilized to match the indented configuration ofside 168. In another variation, a single flange section extending fromeach of sides 172, 174 is used. Fastener 160 also includes insertsection 180 which extends from body section 162. In forming joint 120,insert section 180 is positioned within interior cavity 144 of secondframe member 140. Insert section 180 has a cross-section that fits inand is complementary to the cross-section of second frame member 140.Fastener 160 further includes angled stop surface 182 defined by surface184 of body section 162. Angled stop surface 182 is oriented at a matingangle α₂ that matches (i.e., is complementary to) angle α₁ of the secondframe member 140. Accordingly, when insert section 180 is positionedwithin interior cavity 144, first end 152 is adjacent to angled stopsurface 182.

With reference to FIG. 8B, a perspective view of a fastener thatconnects near the end of a side of the first frame member is provided.Again, fastener 190 includes body section 162 and one or more flangesections 164. Flange sections 164 extend from the body section 162.Flange sections 164 attach to side 168 of first frame member 122 exceptwhen this variation attachment is close to an end first frame membersection 122. The flange section 164 only extends from a single side 192of fastener 190. Fastener 190 also includes insert section 180 whichextends from body section 162. Fastener 190 further includes angled stopsurface 182 defined by surface 184 of body section 162. As set forthabove, angled stop surface 182 is oriented at a mating angle α₂ thatmatches (i.e., is complementary to) angle α₁ of the second frame member140. Accordingly, when insert section 180 is positioned within interiorcavity 144 first end 152 is adjacent to angled stop surface 182.

With reference to FIGS. 10 and 11, various views of a cathedral-typewall fastened together by the joint and fastener of the invention areprovided. The frame members, joints, and fasteners of the invention areadvantageously used to construct building enclosures such as patios,sunrooms, greenhouses and the like. FIG. 10 provides an explodedperspective view and FIG. 11 provides a simple perspective view of acathedral wall. Such a wall is merely a representative example in that amultitude of enclosure designs using the components of the presentinvention are possible. Cathedral wall 200 includes center post 202which is connected to window sills 204, headers 206, and floor starter208 via fasteners 160, 190. Lower wall posts 210 are connected to header206 and floor starter 208 via fasteners 160. Corner posts 212 areconnected to header 206 and floor starter 208 via fasteners 160, 190.Also attached to header 206 is upper wall post 214. Cathedral wall 200also includes window units 220, wing fills 222, 224, kick panels 226,and panel top cap 228.

While embodiments of the invention have been illustrated and described,it is not intended that these embodiments illustrate and describe allpossible forms of the invention. Rather, the words used in thespecification are words of description rather than limitation, and it isunderstood that various changes may be made without departing from thespirit and scope of the invention.

1.-15. (canceled)
 16. A joint for attaching frame members together, thejoint comprising: a first frame member, the first frame member includinga first substantially rectangular surface having a first length andfirst width and a second substantially rectangular surface having asecond length and a second width, the first width being greater than thesecond width; a second frame member having a wall that defines a firstinterior cavity, the second frame member including a first end, a secondend, a third substantially rectangular surface, and a fourthsubstantially rectangular surface, the first end being angled relativeto a plane perpendicular to the third substantially rectangular surface;and a fastener comprising: a body section; one or more flange sectionsextending from the body section, the flanged sections attached to a sideof the second frame member; an insert section extending from the bodysection, the insert section positioned within the interior cavity of thesecond frame member; and an angled stop surface defined by a surface ofthe body section, the angled stop surface oriented at a mating anglethat matches the angle of the second frame member such that when theinsert section is positioned within the interior cavity the first end isadjacent to the angled stop surface.
 17. The joint of claim 16 whereinthe first interior cavity has a non-rectangular cross-section.
 18. Thejoint of claim 17 wherein the non-rectangular cross-section issubstantially I-shaped or H-shaped.
 19. The joint of claim 16 whereinthe first and second frame members each individually comprise apultruded component.
 20. The joint of claim 16 wherein the first andsecond frame members each comprise substantially the same cross-section.